PARIS -- It is early evening on one of the last Saturdays before Christmas, and customers at the Hermes shop on the rue Faubourg St. Honore are standing two and three deep at the scarf counter. Sales clerks in dark blazers tirelessly unfurl square after square of brilliantly colored silk, patterned with peonies, toucans and bold geometric shapes.

The crowd in the wood-paneled shop, which sells everything from hunting attire and luggage to fragrances and silk ties, is the usual holiday mix -- mostly Parisian, with fewer of the usual American and Japanese tourists.

But if the clientele looks younger and decidedly more chic than it did a decade ago, and if the crowd looks bigger, much of the credit goes to one man: Jean-Louis Dumas-Hermes.

Since becoming chairman 10 years ago, Dumas-Hermes, a fifth-generation member of the family that founded the company in 1837, has worked to give Hermes (pronounced air-MEZ) a younger image, so that its goods would appeal to say, Lady Di, as much as to the Queen Mother.

Now the company`s products are recognized status symbols. Its silk scarf, which sells for $140 in the United States, and its four-in-hand silk tie for $65, adorn yuppies of all nations.

``He revolutionized the market for Hermes by repositioning the products without changing the quality,`` said Stanley Marcus, chairman emeritus of Neiman-Marcus, which was among the first to carry Hermes merchandise in the United States after World War II.

Indeed, by restructuring, bringing in outsiders and commissioning bolder ads, the 49-year-old chairman not only rejuvenated the image of Hermes, he invigorated sales. Worldwide sales this year at the privately held company are expected to hit $200 million, up from $50 million in 1978.

Sweeping into the Paris store, a space-age carbon fiber briefcase in one hand, Dumas-Hermes, just back from a store opening in San Francisco, addressed the salespeople by name and asked excitedly, but discreetly, how many scarves had been sold.

Hermes said its sells a silk square every 20 seconds. The record for a single day on rue Faubourg St. Honore, the flagship store of its 210 shops and outlets, is 1,200. On this day 886 have sold.

Upstairs in his office, a sanctuary that adjoins a roof garden filled with fruit trees, the dapper chairman talked about tradition and transformation at his 150-year-old company.

Founded as a harness-making business by Thierry Hermes, the great-great- grandfather of Dumas-Hermes, the company got into travel specialties and golf accessories when the founder`s grandson, Emile-Maurice, took control in the 1920s.

Emile-Maurice also opened the first branch stores in French resort towns, further linking the Hermes name with luxury and leisure. The retail outlet on rue Faubourg St. Honore opened in 1922.

Surrounded by this lore, Dumas-Hermes said in lightly accented English, he got his Hermes education unconsciously: ``We would all gather around the lunch table every day and my father would talk about `that-beautiful-silk-scarf- please-don`t-eat-with-your-hands.` That sort of thing.``

As a young man in Paris, his ambition was to travel, his avocation was jazz. In the 1950s, after studying political science and law, he began a brief career as a drummer, a job that took him to Scandinavia and Czechoslovakia.

``I was a brilliant impresario,`` he joked, improvising on imaginary drums as he spoke. ``We each got 50 francs a night.``

He later traveled through Iran and was a contributing editor to the Pakistan Times. In 1961, he took his compulsory officer training in Algeria. All the while, he gently resisted the pull of Hermes.

``I had nothing against it,`` he said. ``I just had another life.``

In the early 1960s, when his father, Robert Dumas, then company president, told him it was time to come home to Hermes, he agreed. But first he spent a year in New York, in Bloomingdale`s buyer-training program. His wife, Rena, whom he married in 1962, worked in a New York architecture firm.

It was at Bloomingdale`s that he ``discovered the importance of being a merchant.`` At home, at Hermes, he said, ``we were proud to sell, but far more proud to produce.``

When he finally arrived at Hermes in 1964, his first lesson was in humility, he said. His father sent him to the Drouot antiques auctions to choose prints for scarf designs, but not one of his selections was used by the designers at Hermes.

He was more successful as head of manufacturing, and by 1971 was managing director. Seven years later, the family voted him chairman.

His ascendancy surprised him, he said. He is, after all, the fourth, not the first, child in his family. He never assumed that things would automatically go his way at the house of Hermes, where the family was not obliged to be part of the company. His son and daughter have no plans to join Hermes.

``Look, we`re not the Fendi sisters,`` he said, referring to the Italian family that has built a leather-and-fur dynasty.